Electric water heater



July 8, 1947. L. P. HYNES ELECTRIC WATER HEATER Filed Aug. 11, 1944 Patented .luly 8, 1947 UNITED STATES PATENT OFFICE ELECTRIC WATER HEATER Lee P. Hynes, Haddonfield, N. J.

Application August 11, 1944, Serial No. 549,034

11 Claims.

This invention is a water heater or the type in which water contained in a suitable storage tank may be heated by electrical energy.

Heretofore electrical water heaters have been used in which the electrical heating unit is placed inside of a storage tank and in direct contact with the water to be heated. Heaters of this type, however, are objectionable because of electrical corrosion of metal parts due to dissimilar metals immersed in hot water, and also because of the tendency of leakage around the joints of poorly installed pipe connections. Other heaters have also been used in which the electrolytic corrosion of parts has been avoided by employing heating units which are applied externally to the wall of the storage tank containing the water. In some such instances the resistance elements are wound upon a suitable dielectric material, such as mica, which contacts with the tank wall, the whole unit being enclosed in a thin metal covering. While a structure of the last mentioned type overcomes the factors of electrolytic corrosion they are open to the objection of inefiiciency from a thermal standpoint. This is because the heater band radiates heat both inwardly and outwardly, and the outwardly radiated heat is wasted. Even where the heating unit is surrounded by heavy insulation, there will still be a considerable heat loss from the external surface. Another disadvantage of this type of external heater is that it depends upon conducting heat from its inner surface to the tank wall, and it is never possible, because said wall is more or less rough, to have a perfect contact with it. Also if the top connections of the tank should leak, water can drip down and wet the heater and its wiring connections.

One of the objects of the invention is to overcome the foregoing objections by providing an improved means for supporting an electric heating unit around the wall of a storage tank, said unit being so mounted, constructed and arranged as to radiate heat directly to the shell of the water chamber, whereby loss of heat by radiation is minimized. An important object of the invention is to provide a storage tank, so constructed as to provide a maximum heating area for the zone encircled by the heater. A further object is to provide an electrical heater unit having a maximum surface-heating capacity per unit dimensions, which may be readily applied to and removed from the exterior of a storage tank. A further object is to provide a heater of the character mentioned in which the dielectric supporting elements for the electric heating coils are 2 constructed to minimize outward conduction of heat from said coils.

The invention will be hereinafter fully set forth and particularly pointed out in the claims.

In the accompanying drawings:

Figure l is a vertical longitudinal sectional view of a storage heater constructed in accordance with the invention.

Figure 2 is a horizontal sectional view on the line 22, Figure 1.

Figure 3 is an enlarged detail sectional view illustrating the relationship of the heater with the wall of the storage tank.

Figure 4 is a front plan view of one of the dielectric refractory coil-supporting elements.

Figure 5 is an end view of the refractory element.

Referring to the drawings, III designates a closed storage tank having a top head II, and a lower head I2. The side wall of said tank III'ls provided with one or more annular channels or depressions I3, extending inwardly from the peripheral surface thereof. Said channels may be produced in any suitable or desired manner, preferably by rolling. Any number of these channels may be employed, two being shown for purposes of illustration. As clearly shown in Figure 1, the top and bottom Walls I5 and I6 of each channel I3, slope or converge inwardly. This allows sediment to slide off and also eases the stress on the metal when rolling the channel in the tank wall. Extending through the head I2 is a water inlet pipe I8, having a distribution head I9 for discharging water into the tank II) in lateral streams, so as to prevent the jet action of the entering cold water from directing a current upwardly, where it would mix with the stored hot water. Extending downwardly through the head I2 from the upper part of tank In is a hot water outlet pipe Zil. Also extending through the head I2 is a drain pipe 2 I. Each of the pipes I8, 20 and 2| is provided with a suitable valve (not shown) to control the flow of liquid through the respective pipes.

Located within each of the channels I3 is a heater unit HU consisting of a plurality of electrio-heating coils C, mounted in a plurality of porcelain refractory elements R, which are held adjacent the bottom surface of the channel I3 by means of a flexible metal band B, in a manner which will be later described. This band is of sufficient width to cover the open side of the channel I3. It will also be observed that the ends of the elements R lie closely to the flared walls I5 and I6 of the channel I3. Each refractory element R consists of a body portion 25 provided with end flanges 25, each end flange having an opening 21 therein. These porcelain members are of slightly arcuate form in cross section, so as to conform to the external contour of the bottom of the channel 13, in which the heater is to be located. A plurality of said porcelain elements R are removably connected to the band B, side by side, by means of suitable fastening devices 28 which extend through registering holes 21 in the flanges 26 and in the band B. The ends of said band are provided with flanges 29, which are brought together and held in locked relationship by means of suitable bolts 30, so that when the plurality of porcelain units carried by the band B are placed in a channel 13, in a manner to encircle the tank within said channel, the assembled units R will conform to the cross-sectional curvature of the tank, and will be removably secured in their assembled relation within said channel. It will be noted that each of the refractory members R is provided with a plurality of transverse grooves (it which form seats for resistance coils C. These grooves 3| have a depth greater than the diameter of the coils, so that the latter are spaced inwardly from the bottom of the channel l3, and will radiate heat to said bottom through the intervening spaces. It will also be noted that the arched portions 32, which provide the grooves 32, are intersected by recesses 33, so that when the heater units are in their proper assembled relation, encircling the tank, heat will be radiated from the coils C to the adjacent bottom surface of the groove [3, through the spaces between said arche 32. It will also be noted that the back of each dielectric element is provided with a longitudinal recess 34, which will cooperate with the band B, when the parts are assembled, to provide an air insulating space. If desired, the inner faces of each band B may be highly polished to a reflecting surface so as to greatly reduce heat transfer outwardly through the heater unit.

It is preferred to enclose the tank In by an outer jacket 35, which encloses insulation material I designed. to completely cover and enclose the storage tank. This jacket may be made in sections, with removable bands 36 opposite each heater location, so that any time after complete assembly of the tank and insulation, the heater unit itself can be removed or applied without disturbing the arrangement and with no tools other than a screw driver or a pair of pliers. Circular flanges 31 are preferably welded around the tank above and below each channel l3, to space and support the heater band B in proper position, so that the heater will register in the channels l3 without touching the top and bottom walls thereof. Said flanges also function to support the insulation above and below them to keep it in place while the insulation over the heater and under the jacket 36 is removed, so that access may be had to the heating element.

Located opposite each heater band and connected therewith is a terminal box 49 which, when the heater unit is clamped around the tank l8, projects outwardly through an opening provided in the insulation band 35. This box gives convenient access for making the electrical connections to the heater coils. If desired, where two or more heater units are applied, each one may be provided with a thermostat 4!, diagrammatically illustrated in Figure 1. The object of having two or more heater bands is to allow for zone heating, and the thermostats are so positioned as to be influenced by the temperature of the water at selected zones within the tank it. In this way each heating unit may be independently controlled to operate in response to temperature conditions that exist in its vicinity.

It is preferred to construct the refractory elements R of porcelain, which is a reasonably good thermal insulator, and to glaze the surfaces, so that they will reflect the heat toward the bottom surface of the channel l3. Each coil C is also in the form of an open helix, so that the rear portions of the coils can radiate heat outwardly tween the front portions, so that a very efficient one-way heat transfer is accomplished, to the exact point where it is needed to heat the water.

The advantages of the invention will be readily understood by those skilled in the art to which it belongs. For instance it will be observed that by placing the heater units within the inwardly located annular channels, they are located inside of the tank within the water space thereof, so that added heating surface is obtained because the submerged top and bottom walls, as well as the vertical face of the bottom of the groove wall will be heated and will conduct heat to the water within the storage tank. Low heat density per unit of surface is very important in water heating, and this added surface, due to the shape of the channel [3, is a decided advantage in this regard. Another important advantage is that the heater coils are located in grooves on the interior surface of the porcelains, so that they radiate their heat directly to that portion of the wall of the tank which is provided by the channel l3. and as the resistance coil is an open helix, the rear portions of the coils can radiate heat outwardly between the porcelain and the metal tank wall, so that a very efficient one way heat transfer is accomplished to the exact location where it is needed to heat the water. An important advantage of placing the heat unit within an annular channel formed in the wall of the tank is that the channel allows the external surface of the heater to lie approximately flush with the external surface of the tank, so that there is n substantial projection of the heater from said surface. Another advantage in this connection is that by avoiding such projection of the heater unit, there will be no substantial reduction of the thickness of the heat insulation covering at this zone. Another important advantage is that by maintaining the porcelain elements out of contact with the bottom of the annular channel, strain upon said elements, such as would tend to .prevent their expansion when heated, is avoided. This arrangement also insures a tight joint between the carrier band of the heater unit and the tank wall, above and below the channel, so that insulation and other foreign matter is prevented from entering said channel. A further advantage is that the porcelain refractories have air spaces between the flexible steel band and their rear surfaces, thus greatly reducing conduction of heat to the band. Conduction of heat to the band may also be substantially decreased by imparting a high heatreflecting polish to the inner surface of Another advantage is that the dielectric units are independently connected to their supporting band and so spaced that they are free to move with respect to each other so as to conform to the flexible adjustment of said strip.

Having thus explained the nature of the invention and described an operative manner of constructing and using the same, although without attempting to set forth all of the forms in which it may be made, or all of the forms of its use, what is claimed is: r

1. An electrical heater of the character de scribed having in combination a storage tank closed by top and bottom end heads, means for supplying water to and removing the same from said tank, the side wall of the tank having pressed thereinto an annular depression integral with said side wall extending radially into the space normally occupied by the said water, inwardly inclined wall portions connecting said depression with the walls of said tank, an electric heater unit located within said depression adjacent the innermost wall of the latter, the radial depth of said depression being such that the heat emanating from said heat unit is directly applied to the water at a location submerged therein. and covering means for the open side of said de-- pression for enclosing said heating unit.

2. An electrical heater of the character described. having in combination a storage tank I closed by top and bottom end heads, means for supplying water to and removing the same from said tank, the side wall of the tank having an annular depression therein extending radially into the space normally occupied by the said water, an electric heater unit located within said depression, said heater unit including a flexible band of dielectric material having one of its faces located adjacent to the innermost wall of said depression, said adjacent face of said dielectric band having grooves therein and resistance coils within said grooves, the radial depth of said depression being such that the heat emanating from said heat unit is directly applied to the Water at a location submerged therein.

3. An electrical heater of the character described having in combination a storage tank closed by top and bottom end heads, means for supplying water to and removing the same from said tank, the side wall of the tank having an annular depression therein extending radially into the space normally occupied by the said Water, an electric heater unit located within said depression, said heater unit including a flexible band of dielectric material having one of its faces located adjacent to the innermost wall of said depression, said adjacent face of said dielectric band having grooves therein and resistance coils within said grooves, each of said grooves having a depth greater than the diameter of the coil, so that the latter are out of contact with said innermost wall, the radial depth of said depression being such that the heat emanating from said heat unit is directly applied to the water at a location submerged therein.

l. An electrical heater of the character described having in combination a storage tank closed by top and. bottom end heads, means for supplying water to and removing the same from, said tank, the side wall of the tank having an annular depression therein extending radially into the space normally occupied by the said water, an electric heater unit located, within said depression adjacent the innermost wall of latter, said heater unit including a plurality of flexibly connected porcelain refractory members having glazed surfaces and carrying electric heater coils which are exposed to but spaced from innermost wall, the radial depth of said depression being such that the heat emanating from said heat unit is directly applied to the water at a location submerged therein.

5. An electrical heater of the character described having in combination a storage tank closed by top and bottom end heads, means for supplying water to and removing the same from sa d tank, the side wall of the tank having an annular depression therein extending radially i to the space normally occupied by the said wa er, an electric heater unit located within said depression. adjacent the'innermost wall of the r, heater unit including a plurality of flexibly connected porcelain bodies hav- "ansverse grooves therein containing electric coils, means for retaining said heater ,t.tl1in said depression with the tops of said grooves closed by said innermost wall of the desion, the depth of the grooves being greater than the diameter of said coils so as to space latter 1; said innermost wall, the radial depth of said depression being such that the heat emanating from said heat unit is directly applied to the water a location submerged therein,

An electric water heater of the character described having in combination a cylindrical, vertically disposed storage tank closed by top and bottom end heads, means for supplying water to ironnected end \vith-zflrawing it from said tank, the side Wall of s d tank having a plurality of annular heater therein extending radially into the space Y ich is normally occupied by said water, an electric heater unit located within each of said c i kets d 'acent the innermost wall of the latter,

units including a plurality of flexibly refractory insulators which have transversely disposed arched conductory-retaining portions, said insulators being so relatively spaced that the individual insulators are free to mo e with respect to each other and one or more flexible electric conductors supported by said insulators at locations to radiate heat through said insulators to said innermost wall, the radial depth of each of said heater pockets being such that heat emanating from the respective heater unit will be directly applied to the water at a location submerged therein.

7. electrical heater of the character described having in combination a storage tank closed by top and bottom end heads, means for supplying Water to and removing the same from said tank, the side wall of the tank having an annular depression therein extending radially into the space normally occupied by the said water, relatively spaced annular flanges respectively positioned above and below said depression, a flexible band located between said flanges at a position opposite the open end of said depression, a plurality of dielectric members carried by said band and extended into said depression to a position adjacent the innermost wall of the latter, the face of each dielectric member which is adjacent said innermost wall having grooves therein, resistance coils carried by said dielectric elements, and means for retaining said flexible band in place.

8. An electrical heater of the character described having in combination a storage tank closed by top and bottom end heads, means for supplying water to and removing the same from said tank, the side wall of the tank having an annular depression therein extending radially into the space normally occupied by the said water, relatively spaced annular flanges respectively positioned above and below said depression, a flexible band located between said flanges at a position opposite the open end of said depression, a plurality of dielectric members carried by said band and extended into said depression to a position adjacent the innermost wall of the latter, the face of each dielectric member which is adjacent said innermost wall having grooves therein, resistance coils carried by said dielectric elements, the inner face of said band having a reflecting surface, and means for retaining said flexible band in place.

9. An electrical heater of the character described having in combination a storage tank closed by top and bottom end heads, means for supplying water to and removing the same from said tank, the side Wall of the tank having an annular depression therein extending radially into the space normally occupied by the said water, an electric heater unit located within said depression adjacent the innermost wall of the latter, the radial depth of said depression being such that the heat emanating from said heat unit is directly applied to the water at a location submerged therein, and covering means for the open side of said depression for enclosing said heating unit, the inner face of said covering means having a reflecting surface to reflect heat rays directly toward said heating means.

19. In an electric fluid heater of the character described, a metal storage tank for containing a body of fluid to be heated, the side wall of said tank being pressed to provide a spaced substantially shallow integral depressed portion, the metal of said side wall connecting the ends of the depressed portion being in converging relationship toward the axis of the tank, and a heater unit positioned exteriorly of the tank and seated Wholly Within said depressed portion, the heater elements of said unit directing their heat by radiation against the said depressed portion and in a direction toward the axis of the tank.

11. In an electric fluid heater of the character described, a metallic storage tank for containing a body of fluid to be heated, the side wall of said tank being pressed to provide an annular substantially shallow depressed portion, said depressed portion connecting with the side wall of the tank by end portions converging toward the axis of the tank, a substantially thin heater element exteriorly positioned upon said tank and seated within said depressed portion, the heating elements of said heater disposed in a single layer in close proximity to the wall of said depressed portion so that the heat emanating therefrom will be radiated to the said wall of said depressed portion in a direction toward the axis of said tank.

LEE P. HY NES.

REFERENCES CITED The following references are of record in the fiie of this patent:

UNITED STATES PATENTS Numb er Name Date 1,328,723 Curless Jan. 20, 1920 1,695,801 Dibble Dec. 18, 1928 1,820,514 Waller Aug. 25, 1931 2,289,204 Milton July 7, 1942 1,370,619 Whitehead Mar. 8, 1921 

